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XR/CRF 100/80 Rev Limiter?

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From what ive heard, the 80's and 100's have a cut off at about 9800 rpm, but im thinking what exactly is a cut out? Is that simply rev limiter? We have tried revving our bikes before to not find anything because we are too scared of it blowing up, but the other day I tipped over and full throttled it accidentally and I could have sworn I heard rev limiter, ive seen much talk about this before and im eager to find out if they do come stock with a rev limiter because I am baffled to think what else it could have because the whole point of a rev limiter to keep it from exploding and blowing up so what else it could have? My friend has an XR100 with a rev box and I can tell it has more power and speed but yet again we've tried revving it to find nothing but I personally think they do have rev limiters its just that they are to constricting with the small intakes and exhausts to hit these. With some after market parts and tuning I think we would find a rev limiter. What do you think?

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I'd say you're probably right. With the cam profiles, intake and exhaust, I can't see any XR revving 9800 rpm under any kind of load. They're designed for low/mid range for beginner trail riders, and the only way it's going to 10 grand is with a bunch of pit bike modding. Do it too many times with the stock bottom end and I figure you'll be needing a broom, dustpan, and some oil dry.. 

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 First, You shouldn't be trying to find the rev limiter on purpose on an unloaded engine. The limiter will protect a healthy engine in normal running conditions. Free revving an old worn engine can do damage before you get to the limiter.

You probably did bounce off the limiter when you fell over with it pinned. Or the valves floated a bit which also results in power loss. The limiter should hit before valve float by design, but on an old engine who knows.

The reason that your friends bike with a different CDI feels stronger is because the ignition curve is different. It advances sooner and maybe further. Those stock Honda XRs are kids bikes and set up very conservatively for safety and longevity. It could also possibly have a higher rev limit, but really there is no point to that because chances are the exsisting limit is well past the HP peak.

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XR100's have no rev limit.  you can get them to rev to 14k, but peak power is about 9400.  Dyno1.jpg

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As to your friends bike having more power...
Is he using any kind of power booster?
We use it sometimes, it works for us. 

turbo108octaneboost2.png

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 First, You shouldn't be trying to find the rev limiter on purpose on an unloaded engine. The limiter will protect a healthy engine in normal running conditions. Free revving an old worn engine can do damage before you get to the limiter.
You probably did bounce off the limiter when you fell over with it pinned. Or the valves floated a bit which also results in power loss. The limiter should hit before valve float by design, but on an old engine who knows.
The reason that your friends bike with a different CDI feels stronger is because the ignition curve is different. It advances sooner and maybe further. Those stock Honda XRs are kids bikes and set up very conservatively for safety and longevity. It could also possibly have a higher rev limit, but really there is no point to that because chances are the exsisting limit is well past the HP peak.

Didnt say I was, im just curious and wanted to find out. I take care of my bikes and dont rev the piss out of them.

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m1ke2001, we rev the piss out of them.  That was my motor on the dyno test header steps and intake length.  We bumped it that much in a few hours of different configurations.  That was back in the fun days.  But anyway, keep clean oil in it, keep you filter clean, do routine motor maintenance and these motors will last forever.  If you just want to putt it around, there good for that too, but what's the fun in that?

 

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On 5/14/2017 at 10:44 PM, arthur6 said:

As to your friends bike having more power...
Is he using any kind of power booster?
We use it sometimes, it works for us. 

turbo108octaneboost2.png

Where do u buy that stuff? Looking to give it a try 

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